21718961 has 8 divisors (see below), whose sum is σ = 23752224. Its totient is φ = 19695520.

The previous prime is 21718943. The next prime is 21718973. The reversal of 21718961 is 16981712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21718961 - 2⁶ = 21718897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21714961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2645 + ... + 7101.

It is an arithmetic number, because the mean of its divisors is an integer number (2969028).

Almost surely, 2^21718961 is an apocalyptic number.

It is an amenable number.

21718961 is a deficient number, since it is larger than the sum of its proper divisors (2033263).

21718961 is a wasteful number, since it uses less digits than its factorization.

21718961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4911.

The product of its digits is 6048, while the sum is 35.

The square root of 21718961 is about 4660.3606083650. The cubic root of 21718961 is about 279.0056609977.

The spelling of 21718961 in words is "twenty-one million, seven hundred eighteen thousand, nine hundred sixty-one".